In recent years, in mobile communication systems, separate type base station devices that include base band units (BBU) and remote radio heads (RRH) have been widely used. The BBU is a device that performs a connection with a higher-level core network and that performs a baseband process.
The RRH is a device that amplifies an analog signal and that performs a wireless connection with mobile terminals and is also called remote radio equipment. The RRH is connected to the BBU via optical fibers and an overhang of 20 km or more is possible. Furthermore, the RRH is connected to an antenna control device that performs tilt control and state monitoring of an antenna. The RRH and the antenna control device are usually connected via an AISG interface conforming to a standard defined by the Antenna Interface Standards Group (AISG). The AISG interface is defined such that, in addition to an Operations Administration Maintenance (OAM) signal used for maintenance management, a predetermined voltage (for example, +24 V±3 V) is supplied as power source of the antenna control device.
Furthermore, in the RRH, a power amplifier that amplifies a transmission signal is included. The voltage of the power source of the power amplifier is usually higher than the voltage of the power source of the antenna control device. Thus, on the RRH, a power supply device that generates the voltage of power source for the power amplifier and a power supply device that generates the voltage of power source for the antenna control device are separately mounted. Related-art examples are described in Japanese Laid-open Patent Publication No. 2001-332985 and No. 2013-26892.
The antenna control device may sometimes be operated due to area interpolation that occurs when an adjacent base station device is failed. However, because a failure of the base station device does not occur so often, the frequency of operation of the antenna control device is quite low, for example, for few minutes once every few months. Although the frequency of use is low, because the RRH has mounted thereon the power supply device for the antenna control device, reducing the size and the weight of the RRH is difficult.
It is conceivable that the power source for the power amplifier and the power source for the antenna control device are generated from a single power supply device in a shared manner. However, because the power amplifier is operated by the power source with a voltage higher than that of the power source for the antenna control device, if the power source with the voltage for the antenna control device is supplied to the power amplifier, it is difficult to sufficiently obtain the performance, such as the gain or the distortion characteristics of the power amplifier.